delta Go = -431.16kJ/mol - (298k X 0.12529 kJ/K*mol)
I am having trouble converting the units for delta H and delta s to match. I multiplied delta H by 1000 to get kJ but this didn't give me the correct answer.
Chemistry(Please help) - Dev, Wednesday, April 25, 2012 at 6:56pm
If your answer is in J then multiply -431.16 by thousand and you delta S .12529. Make sure all your unit are in J/mol K and Temperature in K.
Chemistry(Please help) - Nem, Wednesday, April 25, 2012 at 6:58pm
-468496.42 J
Chemistry(Please help) - DrBob222, Wednesday, April 25, 2012 at 10:02pm
delta H is usually listed in kJ/mol and S in units of J/mol. Most of the time I want to use dG I must convert it to J so I usually convert delta H to J (1000 x delta H in kJ/mol = delta H in J/mol) and that will match S in J/mol. That will give you dG in J/mol.
I did -431.16kJ/mol X 1000 = -431160
Then -431160 - (298 X 0.12529 kJ/K*mol) = -431197.33 for delta G but this answer was said to be incorrect, I do not know why??
Hannah, you converted BOTH. You don't do that. You convert one or the other, not both. Convert 431.16 kJ to J = 431,160 J and use S as 125.29 OR convert S of 125.29 J/mol to kJ = 0.12529.
So 431,160 - 298*125.29 = ? dG in J or
431.16 - 298*0.12529 = ? dG in kJ.
I go the dG in J route especially if I intend to use this to calculate K
To convert units for delta H and delta S to match, you need to ensure that both quantities are in the same unit. Delta H is usually expressed in kilojoules per mole (kJ/mol), while delta S is typically given in joules per mole Kelvin (J/mol K).
To convert delta H to the intended unit, you can multiply it by 1000 to convert from kJ/mol to J/mol. So, in this case, -431.16 kJ/mol would become -431160 J/mol.
Next, you can calculate delta G using the formula:
delta G = delta H - (T * delta S)
In your calculation, you need to make sure that the temperature (T) is in Kelvin. Assuming 298 K is the temperature, you can proceed as follows:
delta G = -431160 J/mol - (298 K * 0.12529 J/mol K)
= -431160 J/mol - (37463.42 J/mol)
= -468623.42 J/mol
Note that I rounded the final answer to two decimal places, which gives us -468623.42 J/mol. It seems that there was a slight discrepancy between your calculation and the correct answer. Hence, the answer provided to you by Nem was incorrect.
I hope this helps clarify the process of converting units and calculating delta G. If you have any further questions, please feel free to ask!